Carbonated beverages have long been available in bottles of volumes of up to 3 liters, quantities which are not generally consumed at a single sitting. Although it may be economical to purchase beverages, e.g., soft drinks, in such large bottles, opening the bottle and resealing it by hand will very often result in an imperfect seal which will cause the liquid to go "flat", i.e., lose its carbonation to the atmosphere.
The most common type of top for soft drink bottles in use today is a screw top made of stamped aluminum with a plastic insert. At the bottling plant, the aluminum cap is generally sealed around the opening in the bottle by means of bendable tabs or a frangibly-connected ring around the rim of the cap. To permit the cap to be removed, when the cap is first unscrewed from the bottle by the consumer, either the bendable tabs will deform to form a larger diameter at the base of the cap, or the frangibly-connected ring will break off the cap and remain around the neck of the bottle. If the contents of the bottle are not entirely consumed at once, the consumer will naturally want to reseal the bottle with the original cap. The original cap, however, will not be able to effect the efficient seal created at the bottling plant after the bottom tabs have been distended or the connecting ring has been broken off. Consequently, no matter how tightly the consumer tries to reattach the bottle cap, the carbonation gases will escape from the soft drink through the imperfect seal, leaving the beverage flat.
The engineering problems associated with maintaining carbonation of a liquid in a container are identical to those of the general problem of maintaining a gaseous seal between the interior and exterior of a container. Thus, although the present invention is primarily intended to maintain carbonation in a bottle, the apparatus may be used in a variety of contexts where gaseous interchange between the interior and exterior of a bottle is to be avoided. For example, a non-carbonated liquid which gives off harmful fumes, such as turpentine, may be inoffensively but conveniently stored in a container incorporating the present invention. The apparatus of the present invention may also be used to create a seal for containers of liquids that may easily be contaminated by bacteria, such as baby formula. And, of course, the apparatus may be used to maintain carbonation in beverages which are not soft drinks, such as beer or sparkling wine.
An object of the present invention is to provide a resealable cap which may be placed on containers which have been previously opened. The consumer, having broken the seal of the original aluminum cap, may subsequently use the reusable cap of the present invention to maintain carbonation of the liquid while it is being consumed over the course of several openings of the bottle. The present invention creates a gas tight seal between the interior of the bottle and the outside atmosphere.
Another object of the invention is to provide a reusable cap for carbonated beverage bottles which will effect a reliable seal without obliging the consumer to follow complicated directions.
Another object of the invention is to provide a reusable cap for carbonated beverage bottles, in which the integrity of the seal is maintained by the outward gaseous pressure of the carbonation itself.
Another object of the invention is to provide a reusable cap capable of maintaining a gaseous seal between the interior and exterior of a container.
Other objects will appear hereinafter.